Local caching of images for on-line conferencing programs

[0001] This invention relates to multiparty communications over computer networks.

[0002] In on-line meeting software, a presenter can distribute various images via a communications network to other meeting participants such that each participant is simultaneously viewing the same image on his or her computer. By way of example, the image may be a slide created by presentation graphics software. Meeting participants may then discuss a commonly displayed image by, for example, on-screen text messaging or chat windows, video phones or conventional telephone conference calling.

[0003] With conventional systems, if the meeting participants wish to return to a previously sent slide for further discussion, the image must be resent from the meeting presenter's computer to each participant's computer. This is a time-consuming process inasmuch as images typically comprise large amounts of data and the data must be sent over communications channels having finite bandwidths.

[0004] Thus, there is a need for a way to facilitate on-line conferences.

[0005] FIG. 1 shows networked, processor-based systems comprising one embodiment of the present invention;

[0006] FIG. 2 is a software flow chart for one embodiment of the invention;

[0007] FIG. 3 is a flow chart for another embodiment of the invention; and

[0008] FIG. 4 is a flow chart for another embodiment of the invention.

[0009] FIG. 5 is a flow chart for another embodiment of the invention.

[0010] A network 32 includes at least two client processor-based systems 8, as shown in FIG. 1. The network 32 may be a wired or wireless local area network (LAN) in one embodiment of the present invention. Each system 8 may include a processor 38 coupled to a display 34 and a storage device 42. The processor-based system 8a may be used by the presenter in an on-line meeting or conference set up between a presenter and one or more participants. The system 8b may be used by a participant.

[0011] Both systems 8 may be personal computers in one embodiment and the storage 42 may be, for example, a magnetic media disk drive with associated disk controllers or solid-state memory such as random access memory (RAM). The system 8b storage 42 may store software 40 for enabling the processor 38 to participate in a network presentation as well as the data 30 to be presented. The system 8a storage 42 may store software 50 for implementing a network presentation.

[0012] The software 40 may operate as part of or work with on-line conferencing software. An example of on-line conferencing software is NetMeeting software from Microsoft Corporation, Redmond, Wash.

[0013] An on-line meeting may be set up between a presenter system 8a and one or more participant systems 8b by establishing communications over a network 32, as indicated at block 10 of FIG. 2. The presenter's system 8a may send data to each of the participant systems 8b. The shared data may be, for example, a series of images or frames. The presenter's system 8a may send each image when the presenter desires to change the image displayed for viewing by the participants.

[0014] The presenter may have created the images with presentation graphics software and the images may comprise slides. Each slide may have a unique identifier that may be, for example, a file attribute of the data comprising the image.

[0015] During the course of the on-line meeting, the presenter's system 8a may send data relating to a slide to participant systems 8b, as indicated at block 14. As shown at diamond 18, a participant's system 8b may determine, for example by testing the slide identifier, whether the slide being sent by the presenter's system 8a is a new slide or a previously-sent slide. Multitasking techniques may be employed by a participant's system 8a to compare the identifier with the identifiers of cached images while the session is still in progress.

[0016] If the slide is a previously-sent slide, it may be available in a local cache of slides and may be retrieved from the cache, as indicated at block 22. The cached slide may be displayed, as indicated at block 26, on the participant's processor-based system 8b.

[0017] If the slide is in the local cache, the transmitted image data may be directed to a bit bucket while the cached slide is retrieved and displayed as indicated at blocks 22 and 26, respectively. A bit bucket is an imaging location into which data can be discarded.

[0018] If, however, the slide is not in the cache, the slide may be downloaded from the presenter's system 8a over the network 32, as indicated at block 20, and subsequently cached and displayed, as indicated at blocks 24 and 26, respectively. In this way, participants who join the meeting late may download a slide previously sent to other participants without delaying the image viewing by the earlier-joining participants whose systems may have the slide in their local caches.

[0019] Inasmuch as data can typically be retrieved from a local cache more quickly than it can be downloaded via a network 32, participants in an on-line meeting can save time whenever the presenter returns to a previously-sent slide for discussion that is already available in a participant's system 8b.

[0020] If the meeting is concluded, as indicated at the right branch of diamond 28, the participant system 8b may disconnect from the session as indicated at block 30. The meeting may be over when an indicating signal is sent from the system 8a to the system 8b in one embodiment. If the meeting is not over, as indicated by the lower branch of diamond 28, the participant's system 8b may query the presenter to determine whether the presenter has changed his or her system to edit mode, as indicated at diamond 12.

[0021] Graphics generating programs may have multiple modes of operation. For example, a software package for presentation graphics may have an editing mode wherein slides are created and modified and a presentation mode or slide show mode wherein a predetermined sequence of slides is displayed seriatim.

[0022] The presenter may desire to edit the presentation graphics during the course of an on-line meeting. In such a situation, the presenter may change the state of the system 8a from a presentation mode to an editing mode. If the presenter alters one or more images on his or her system, one or more images which may have been cached by the participants' systems may no longer correspond to the images stored by the presenter's system 8a even though the images may have the same identifier. In such an instance, a participant system 8b local cache is stale and should be flushed, as indicated at block 19i.e., cleared from the data storage sub-system of a participant's system as though no images were cached.

[0023] The presenter's system 8a may broadcast a message or code that indicates to all participant systems 8b that the presenter has switched his or her system to editing mode. In response, each participant's system 8b local cache may be flushed, as indicated at block 19. Alternatively, each participant system 8b may query the presenter's system 8a regarding its mode, as indicated at diamond 12. If the presenter's system 8a responds that it is in edit mode, the participant's system 8b may flush its local cache, as indicated at block 19. In yet another alternative, the presenter's system 8a may indicate which image or images have been altered and, in response, the participant's system 8b may flush only those images from its local cache.

[0024] In this way, a meeting participant's system 8b may build a local cache of slides during the course of an online meeting as the meeting presenter's system 8a sends individual slides, seriatim. During a meeting, because a participant's system 8b is able to retrieve previously-sent slides from a local cache, the images may be displayed more quickly than if the image data is again downloaded from a network 32.

[0025] In another embodiment, an on-line meeting presenter's system may send a slide identifier (but initially not image data) to meeting participant system 8b, as indicated at block 15 of FIG. 3. The presenter system 8a may then wait for a request from a participant system 8b for the image data comprising the slide.

[0026] As indicated at block 17 of FIG. 3, a meeting participant system 8b may determine from the slide identifier whether the slide exists in its local cache. If the slide is found in the local cache, it may be retrieved from the cache 22 and displayed, as indicated at blocks 22 and 26, respectively.

[0027] If, however, the image data comprising the slide is not found in the local cache, as indicated at the right branch of diamond 17, the participant system 8b may request the slide from the presenter system 8a, as indicated at block 21. The presenter system 8a may, in response, send the requested slide, as indicated at block 16, which data may then be stored by the participant system 8b in its local cache and displayed, as indicated at blocks 24 and 26, respectively.

[0028] In this embodiment, the presenter system 8a need not send the image data comprising the slide if all participant systems 8b already have the slide in their local caches i.e., if no participant system 8b requests a download of the image data. In this way, both time and network resources may be conserved.

[0029] In yet another embodiment, cache-participants may receive a download of a slide during the course of an online meeting and subsequently determine whether a cached version differs from the downloaded version. In the meantime, the cached version may be displayed. The presenter's system 8a may send data relating to a slide to participant systems 8b, as indicated at block 14 of FIG. 5. A participant's system 8b may extract a slide identifier from this data as shown at block 15a. As shown at diamond 17, a participant's system 8b may then determine, for example by testing the slide identifier, whether the slide being sent by the presenter's system 8a has the same identifier as a previously-sent slide. Multitasking techniques may be employed by a participant's system 8a to compare the identifier with the identifiers of cached images while the session is still in progress.

[0030] If the slide identifier corresponds with that of a previously-sent slide, it may be available in a local cache of slides and may be retrieved from the cache, as indicated at block 22. The cached slide may be displayed, as indicated at block 26a, on the participant's processor-based system 8b along with a warning to the viewer that the slide may not correspond with that of the presenter's system.

[0031] As indicated at block 20, the download of image data may be completed by the participant's system. As indicated at diamond 23, the just-downloaded image data may then be compared to the cached image data having the same slide identifier to determine whether there has been any change in the data. If no change is detected, the warning on the display may be removed as indicated at block 26c. If, however, a change is found, the just-downloaded data may be stored in the cache replacing the previously stored data having the same identifier, as indicated at block 24a. The displayed image may then be updated using the new data and the display warning removed as indicated at blocks 26b and 26c, respectively. If the changes in the image data are minimal, display techniques may be employed to smoothly morph the image from the previous version to the more recent one.

[0032] If, however, the slide is not in the cache as indicated by the left branch of diamond 17, the slide may be downloaded from the presenter's system 8a over the network 32, as indicated at block 20a, and subsequently cached and displayed, as indicated at blocks 24 and 26, respectively.

[0033] In this way, the speed of a cache-based system may be realized whenever the meeting participants return to a previously sent slide even if the image must subsequently be modified due to a change in the image by the presenter.

[0034] Referring to FIG. 4, the software 50 on the presenter system 8a may implement the caching protocol in conjunction with the participant systems 8b. Initially, the presenter system 8a establishes the network meeting as indicated in block 52. Information may be sent to the participants concerning each slide as indicated in block 54. In some embodiments, this may include the initial download of a portion of the slide. In other embodiments, only an identifier for the slide may be provided. If only an identifier is provided, then the information is not sent until the participant indicates that it actually wants the download. If only a portion of the slide is provided, the same protocol may be utilized or, the information may be transmitted even if the participant determines that it will not receive the information.

[0035] If the download is requested as determined in diamond 56, the data may be sent as indicated in diamond 58.

[0036] In another embodiment, the network 32 may be the Internet. In such case, the systems 8 may communicate and send slides or other data over the Internet.

[0037] While the present invention has been described with respect to a limited number of embodiments, those skilled in the art will appreciate numerous modifications and variations therefrom. It is intended that the appended claims cover all such modifications and variations as fall within the true spirit and scope of this present invention.